1. Field
Aspects of embodiments of the present invention relate to a resin film and a method of manufacturing the resin film.
2. Description of the Related Art
As disclosed in JP2004-109966 A and JP2006-336008 A, for example, an anti-reflection film is often adhered to a surface of a liquid crystal display, a plasma display, and the like. The anti-reflection film serves to prevent light reflection at the surface of the display, thereby improving visibility of the display. A conventional anti-reflection film has a low refractive index layer having lower refractive index and a high refractive index layer having higher refractive index than that of the low refractive index layer.
The low refractive index layer includes hollow silica particles, an acrylic resin, a fluorinated acrylic resin, and additives. The hollow silica particles are silica particles of a hollow structure and serve to reduce an index of refraction of the low refractive index layer. The acrylic resin serves as a binder which binds the hollow silica particles to one another. The fluorinated acrylic resin serves to bind the hollow silica particles to one another, while reducing the index of refraction of the low refractive index layer.
The additives are coupled to hollow silica particles distributed on a surface of the low refractive index layer, thereby imparting antifouling properties and slip properties to the low refractive index layer, that is, to the anti-reflection film. Examples of such additives may include silicon polymers and fluoropolymers. The additives are present on the surface of the low refractive index layer in order to properly function.
However, in a conventional low refractive index layer, additives are distributed not only on the surface of the low refractive index layer, but also inside the low refractive index layer as well. For example, the reason why the additives are distributed inside the low refractive index layer is that hollow silica particles and fluorinated acrylic resin disrupt “bleed-out” (migration to the surface of the low refractive index layer) of the additives. In other words, the additives cannot effectively move to the surface due to the hollow silica particles acting as a barrier. In addition, the additives exhibit affinity with the fluorinated acrylic resin. For example, since both fluoropolymers and fluorinated acrylic resins include fluorine, they are likely to have high affinity with each other, which can cause the additives to stay in the vicinity of the fluorinated acrylic resins.
Accordingly, in the conventional low refractive index layer, the additives cannot be effectively localized at the surface of the low refractive index layer. As a result, although the conventional low refractive index layer initially exhibits good antifouling properties and slip properties, the low refractive index layer suffers from significant deterioration in these properties after repeated surface wiping.
Further, the conventional low refractive index layer has a problem in that the additives distributed inside the low refractive index layer reduce crosslinking density of binder resins (i.e. an acrylic resin and a fluorinated acrylic resin), thereby causing deterioration in film strength. Specifically, the additives (particularly, fluoropolymer) have repellency to the acrylic resin. Thus, the acrylic resin is unlikely to be distributed around the additives, thereby causing reduction in crosslinking density of the acrylic resin.
JP2004-109966 A discloses a technique in which a surface of a hard-coat layer is formed in a convex-concave shape, followed by forming a low refractive index layer on the surface of the hard-coat layer, thereby obtaining a convex-concave low refractive index layer. According to this technique, the low refractive index layer is expected to exhibit improved antifouling properties by virtue of the convex-concave shape thereof. However, this technique cannot provide localization of additives at the surface of the low refractive index layer. In addition, this technique has a problem in that the surface of the hard-coat layer needs to be formed in a convex-concave shape so as to obtain the convex-concave-shaped low refractive index layer, which requires intensive efforts.
JP2006-336008 A discloses an anti-reflection film having a sea-island structure composed of a phase not containing silica particles and a phase containing silica particles. However, this technique cannot provide localization of additives at the surface of the low refractive index layer. In addition, in this technique, the anti-reflection film also exhibits very poor durability. Thus, the techniques disclosed in these patent documents cannot solve the aforementioned problems.